Should antioxidant status be considered in interventional trials with antioxidants?

Vitamin E supplementation (alone or with other antioxidants) and stroke: a meta-analysis

CONTEXT

A previous study showed that vitamin E is effective in reducing the incidence of myocardial infarction only when it is taken in the absence of other antioxidants. It is unclear if it also reduces the incidence of stroke.

OBJECTIVE

The aim of this meta-analysis is to compare the effect of vitamin E supplementation alone or combined with other antioxidants on the incidence of stroke.

DATA SOURCES

A search was performed in the following databases: PubMed, ISI Web of Science, SCOPUS, and Cochrane Library.

DATA EXTRACTION

Sixteen randomized controlled trials were selected to evaluate the effect of vitamin E supplementation on stroke.

DATA ANALYSIS

The range of vitamin E doses used was 33-800 IU. The follow-up period ranged from 6 months to 9.4 years. Compared with controls, when vitamin E was given alone it did not reduce the incidence of ischemic and hemorrhagic stroke. Conversely, compared with controls, supplementation of vitamin E with other antioxidants reduced ischemic stroke (random effects, RR: 0.91; 95% CI: 0.84-0.99; P = 0.02) but with a significant increase in hemorrhagic stroke (random effects, RR: 1.22; 95% CI: 1.0-1.48; P = 0.04).

CONCLUSIONS

Supplementation with vitamin E alone is not associated with stroke reduction. Instead, supplementation of vitamin E with other antioxidants reduces the incidence of ischemic stroke but increases the risk of hemorrhagic stroke, cancelling any beneficial effect derived. Thus, vitamin E is not recommended in stroke prevention.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022258259.

Atherothrombosis and Oxidative Stress: Mechanisms and Management in Elderly

SIGNIFICANCE

The incidence of cardiovascular events (CVEs) increases with age, representing the main cause of death in an elderly population. Aging is associated with overproduction of reactive oxygen species (ROS), which may affect clotting and platelet activation, and impair endothelial function, thus predisposing elderly patients to thrombotic complications. Recent Advances: There is increasing evidence to suggest that aging is associated with an imbalance between oxidative stress and antioxidant status. Thus, upregulation of ROS-producing enzymes such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and myeloperoxidase, along with downregulation of antioxidant enzymes, such as superoxide dismutase and glutathione peroxidase, occurs during aging. This imbalance may predispose to thrombosis by enhancing platelet and clotting activation and eliciting endothelial dysfunction. Recently, gut-derived products, such as trimethylamine N-oxide (TMAO) and lipopolysaccharide, are emerging as novel atherosclerotic risk factors, and gut microbiota composition has been shown to change by aging, and may concur with the increased cardiovascular risk in the elderly.

CRITICAL ISSUES

Antioxidant treatment is ineffective in patients at risk or with cardiovascular disease. Further, anti-thrombotic treatment seems to work less in the elderly population.

FUTURE DIRECTIONS

Interventional trials with antioxidants targeting enzymes implicated in aging-related atherothrombosis are warranted to explore whether modulation of redox status is effective in lowering CVEs in the elderly. Antioxid. Redox Signal. 27, 1083-1124.

Influence of Antioxidants on Leptin Metabolism and its Role in the Pathogenesis of Obesity

Obesity is associated with low-grade inflammation. Leptin, a hormone made by fat cells regulates appetite and hunger and thus food intake behavior. Interestingly, , food preservatives like sodium sulfite and sodium benzoate and also natural colorant and spice compounds such as curcumin were found to decrease the release of leptin in murine 3T3-L1 adipocytes, after co-incubation with LPS, which was added to mimic the pro-inflammatory status in obesity. Several of these compounds are well known food antioxidants.Whilst reducing oxidation events is beneficial in states of elevated oxidative stress, overexposure to food antioxidant can lead to adverse effects. There are hints from in vivo data, that antioxidant stress in younger age plays a role in the development of adiposity in later life. The insufficient exposure to oxidizing compounds like reactive oxygen species (ROS) cannot only cause an insufficient burning of calories but there is also a link to the regulation of food intake behavior. If the in vitro findings can be extrapolated to the in vivo situation, consumption of antioxidant supplemented food could lead to decreased leptin release and contribute to an obesogenic environment. This aspect sheds some new critical light on the potential role of an antioxidant-enriched nutrition in the obesity epidemic during the past few centuries. Doing sports could represent not only a proper strategy to initiate physiological ROS production and burning of calories, but also may shift the hormone milieu towards a reduction of hunger feelings and thus reduce appetite and food intake.

Systemic oxidant/antioxidant balance in human abdominal aortic aneurysm

The aim of this study was to evaluate the oxidant-antioxidant balance in patients with abdominal aortic aneurysms (AAA). Forty-two consecutive patients with AAA and 46 control subjects were included. Total oxidant status (TOS) and total antioxidant status (TAS) levels were measured and the oxidative stress index (OSI) value determined. Serum TOS and OSI values in patients with AAA were higher than those in the controls (p<0.001, p<0.001, respectively). There was a positive correlation between abdominal aortic diameters, serum TOS levels (r=0.592, p<0.001) and OSI values (r=0.598, p<0.001). A cut-off value of 17.68 µmol H2O2 equivalent/L for TOS was associated with 86% sensitivity and 83% specificity and a cut-off value of 1.77 for OSI was associated with 86% sensitivity and 81% specificity for predicting AAA. Systemic oxidative imbalance develops in patients with AAA, particularly as a result of an increase in TOS.

Supplementation with vitamin E alone is associated with reduced myocardial infarction: a meta-analysis

BACKGROUND AND AIMS

Previous meta-analyses of interventional trials with vitamin E provided negative results but it remains unclear if this vitamin has some influence on cardiovascular events when supplemented alone. The aim of this study was to compare the effect of vitamin E alone or in combination with other antioxidants on myocardial infarction.

METHODS AND RESULTS

Pubmed, ISI Web of Science, SCOPUS and Cochrane database were searched without language restrictions. We investigated randomized clinical trials studying the effect of vitamin E supplementation on myocardial infarction. Sixteen randomized controlled trials of vitamin E treatment were analyzed in this meta-analysis. The dose range for vitamin E was 33-800IU. Follow-up ranged from 0.5 to 9.4 years. Compared to controls, vitamin E given alone significantly decreased myocardial infarction (3.0% vs 3.4%) (random effects R.R.: 0.82; 95% C.I., 0.70-0.96; p = 0.01). This effect was driven by reduction of fatal myocardial infarction (random effects R.R.: 0.84; 95% C.I., 0.73-0.96; p = 0.01).

CONCLUSIONS

When supplemented alone, vitamin E reduces myocardial infarction in interventional trials while it appears ineffective when associated with other antioxidants.

The good and bad of antioxidant foods: An immunological perspective

Maintenance of redox homeostasis plays a central role in health and disease prevention, and antioxidant foods are thought to exert protective effects by counteracting oxidative stress. The term "dietary antioxidant" implies a classical reducing or radical-scavenging capacity, but more data on the in vivo bioactivity of such compounds are needed. Indeed, several dietary antioxidants activate signaling cascades that lead to effects that extend beyond radical scavenging, such as the induction of endogenous cytoprotective mechanisms and detoxification. Currently, the overall uptake of antioxidants with diet exceeds actual needs, as food additives that include vitamins, colorants, flavoring agents, and preservatives are often also relatively strong antioxidants. Chronic antioxidative stress favors adverse effects, such as the suppression of T helper (Th) type 1 immune responses and consequent activation of Th2 reactions that support the development of asthma, allergies, and obesity. In this context, we discuss the immunoregulatory pathway of tryptophan breakdown by enzyme indoleamine 2,3-dioxygenase (IDO), which represents a central regulatory hub for immune, metabolic, and neuroendocrine processes. Activation of IDO-mediated tryptophan metabolism is strongly redox-sensitive and is therefore susceptible to modulation by dietary components, phytochemicals, preservatives, and drugs.

Different degrees of NADPH oxidase 2 regulation and in vivo platelet activation: lesson from chronic granulomatous disease

Background

In vitro study showed that NADPH oxidase (NOx), the most important enzyme producing reactive oxygen species (ROS), plays a role in the process of platelet activation. However, it is unclear if changes in its activity affect platelet activation in vivo.

Methods and Results

In vivo and ex vivo experiments assessing platelet activation were investigated in healthy subjects, obese patients, and subjects with different low rates of NOx2 activity, namely X‐linked chronic granulomatous disease (X‐CGD) patients and X‐CGD carriers. We included 27 X‐CGD patients, 31 women carriers of hereditary deficiency of NOx2, 31 obese women, and 62 healthy subjects matched for sex and age. Plasma levels of soluble sCD40 L (sCD40L) and soluble P (sP)‐selectin, 2 markers of in vivo platelet activation, were reduced in X‐CGD patients (sCD40L=−55%; sP‐selectin=−51%, P<0.001) and in X‐CGD carriers (sCD40L=−41%; sP‐selectin=−57%, P<0.001) compared with respective controls. Conversely, obese women, who disclosed NOx2 upregulation, had significantly higher plasma levels of sCD40L (+47%, P<0.001) and sP‐selectin (+70%, P<0.001) compared with controls. Ex vivo study showed platelet isoprostane downexpression and enhanced platelet NO generation in both X‐CGD patients and X‐CGD carriers compared with controls; opposite findings were observed in obese patients. Correlation analysis showed that platelet NOx2 regulation was directly associated with plasma levels of sCD40L (R=0.336, P<0.001) and sP‐selectin (R=0.441; P<0.001).

Conclusions

The study provides the first evidence that in vivo platelet activation is significantly and directly associated with NOx2 activity. Platelet NOx2 may be a novel target for platelet activation inhibition.

Hypercholesterolemia: its impact on ischemia-reperfusion injury

Ischemic diseases are a leading cause of death worldwide. It is becoming increasingly appreciated that atherosclerosis is a major cause of ischemia reperfusion. Hypercholesterolemia is a major risk factor for the development of atherosclerosis, and is associated with an increased incidence of ischemia reperfusion. Furthermore, elevated cholesterol levels exacerbate the vascular responses to ischemia-reperfusion, which intensifies the resulting organ dysfunction. One of the underlying features of both ischemia-reperfusion injury and hypercholesterolemia is the proinflammatory and prothrombogenic phenotype invoked in the microvasculature. This is manifested as an endothelial dysfunction, characterized by leukocyte and platelet recruitment, oxidative stress and angiotensin II receptor Type 1a activation. These common pathways of inflammation offer attractive targets for the development of drugs to combat cardiovascular disease and the associated ischemic disorders.

Antioxidants and diabetes

Hyperglycemia promotes auto-oxidation of glucose to form free radicals. The generation of free radicals beyond the scavenging abilities of endogenous antioxidant defenses results in macro- and microvascular dysfunction. Antioxidants such as N-acetylcysteine, vitamin C and α-lipoic acid are effective in reducing diabetic complications, indicating that it may be beneficial either by ingestion of natural antioxidants or through dietary supplementation. However, while antioxidants are proving essential tools in the investigation of oxidant stress-related diabetic pathologies and despite the obvious potential merit of a replacement style therapy, the safety and efficacy of antioxidant supplementation in any future treatment, remains to be established.

Upstream therapy with statin and recurrence of atrial fibrillation after electrical cardioversion. Review of the literature and meta-analysis

Background

Atrial fibrillation (AF) is the most common sustained arrhythmia observed in clinical practice. Electrical cardioversion (EC) is commonly used to restore and maintain sinus rhythm but it is characterized by high rate of recurrences. Several trials analyzed the effects of statins to reduce the recurrences in AF with contradictory results.

Methods

We performed a meta-analysis of the interventional trials with statins in patients with persistent AF to evaluate recurrences after EC. Only randomized controlled trials were included in the analysis. Data sources included: Medline, ISI Web of Science, SCOPUS and Cochrane database (up to June 2012). Data extraction was performed by three authors. Study-specific odds ratios (ORs) were combined using fixed-effects model.

Results

Six studies with 515 patients were included in the analysis. Statins used in the selected trials were: atorvastatin (at dosages ranging from 10 to 80 mg/day), pravastatin (40 mg/day) and rosuvastatin (20 mg/day). AF recurrence after EC occurred in 108/258 (41.8%) of patients treated with statins and in 132/257 (51.3%) patients not on treatment with statins. Compared with control, recurrences were significantly reduced with statin treatment (O.R.: 0.662; 95% C.I., 0.45-0.96; p=0.03); statin treatment was associated with an absolute risk reduction of 0.095 and a number needed to treat of 11.

Conclusions

This review suggests that statin therapy was significantly associated with a decreased risk of recurrence in patients with persistent AF after EC.

Dark chocolate inhibits platelet isoprostanes via NOX2 down-regulation in smokers

BACKGROUND

Dark chocolate is reported to decrease platelet activation but the underlying mechanism is still undefined. Dark chocolate is rich in polyphenols that could exert an antiplatelet action via inhibition of oxidative stress. The aim of the present study was to assess if dark chocolate inhibits platelet reactive oxidant species (ROS) formation and platelet activation.

METHODS

Twenty healthy subjects (HS) and 20 smokers were randomly allocated to receive 40 g of dark (cocoa > 85%) or milk chocolate (cocoa < 35%) in a cross-over, single-blind study. There was an interval of 7 days between the two phases of the study. At baseline and 2 h after chocolate ingestion, platelet recruitment (PR), platelet ROS, platelet isoprostane 8-ISO-prostaglandin F2α (8-iso-PGF2α), Thromboxane (TxA2) and platelet activation of NOX2, the catalytic sub-unit of NADPH oxidase, and serum epicatechin were measured.

RESULTS

Compared with HS, smokers showed enhanced PR, platelet formation of ROS and eicosanoids and NOX2 activation. After dark chocolate, platelet ROS (-48%, P < 0.001), 8-iso-PGF2α (-10%, P < 0.001) and NOX2 activation (-22%, P < 0.001) significantly decreased; dark chocolate did not affect platelet variables in HS. No effect of milk chocolate was detected in both groups. Serum epicatechin increased after dark chocolate in HS (from 0.454 ± 0.3 nm to 118.3 ± 53.7 nm) and smokers (from 0.5 ± 0.28 nm to 120.9 ± 54.2 nm). Platelet incubation with 0.1-10 μm catechin significantly reduced PR, platelet 8-iso-PGF2α and ROS formation and NOX2 activation only in platelets from smokers.

CONCLUSIONS

Dark chocolate inhibits platelet function by lowering oxidative stress only in smokers; this effect seems to be dependent on its polyphenolic content.

Targeting the vicious inflammation-oxidative stress cycle for the management of heart failure

Oxidative stress and inflammation are each implicated independently in the development and progression of heart failure. Their interaction, however, is also evident throughout the process from initial injury to cardiac remodeling and failure. In the failing heart, the linkage between excessive reactive oxygen species (ROS) and the cytokine elaboration is manifested in shared elements and cross-promotion within downstream signaling pathways. In spite of this, the failure of anticytokine immunotherapy and antioxidant therapy, which had previously shown promise, suggests that a more complete perspective of ROS-cytokine interaction is required. The present review focuses on two of the major cytokines that are demonstrably connected to oxidative stress--the pro-inflammatory tumor necrosis factor-alpha (TNF-alpha) and the anti-inflammatory interleukin-10 (IL-10)--and their interactions in cardiac remodeling and failure. It is proposed that an optimal balance between TNF-alpha and IL-10 may be of crucial importance in mitigating both inflammation and oxidative stress processes leading to heart failure.

Targeting reactive oxygen species in hypertension

Oxidative stress plays an important role in the pathogenesis of hypertension. A number of sources of reactive oxygen species have been identified including NADPH oxidase, endothelial NO synthase, and xanthine oxidase. Inhibitors of these systems reduce blood pressure in experimental models. Targeted overexpression of antioxidant systems and interference with expression of oxidant systems has also been successfully used in animal models of hypertension. It is expected that these strategies will eventually be translated to human disease, but currently, the specificity and toxicity of such measures are not yet fulfilling quality criteria for treatment of humans. In the meantime, presumably nontoxic measures, such as administration of antioxidant vitamins, are the only available treatments for oxidative stress in humans. In this review, we discuss strategies to target oxidative stress both in experimental models and in humans. We also discuss how patients could be selected who particularly benefit from antioxidant treatment. In clinical practice, diagnostic procedures beyond measurement of blood pressure will be necessary to predict the response to antioxidants; these procedures will include measurement of antioxidant status and detailed assessment of vascular structure and function.

Statin treatment as a confounding factor in human trials with vitamin E

Interventional trials with vitamin E have been planned on the assumption that it could reduce atherosclerotic progression via inhibition of oxidative stress. These trials have been conducted in patients at risk for or with cardiovascular disease, but the results have been divergent. The reason for the equivocal results is still unclear. We have recently demonstrated that in patients with hypercholesterolemia, the administration of a statin is associated with reduced urinary isoprostanes, a marker of oxidative stress, and normalization of circulating levels of vitamin E, indicating that statins enhance the antioxidant status. Based on these arguments, we reanalyzed the interventional trials with vitamin E to see if concomitant use of statins could have created a potential bias. We reviewed 9 interventional trials, each including > 1000 patients. In 5 of the 9 trials, the concomitant use of statins was reported. In the arm randomized to vitamin E, a concomitant use of statins was reported in at least one-third of the population. In some trials, the percentage of patients given statins was > 50%, suggesting that a large part of the follow-up population was likely useless treated with vitamin E in view of the concomitant antioxidant effect of statins. Also, the anti-atherosclerotic effect of statins could have reduced the possibility that a prespecified sample size had an adequate power to observe a difference between vitamin E and placebo-treated groups. We therefore suggest that a meta-analysis of trials with vitamin E should be re-done by excluding patients who concomitantly used statins.

Baseline glutathione peroxidase activity affects prognosis after acute coronary syndromes

Oxidative stress is associated with atherosclerosis and plaque lesions in experimental in vitro models. Few in vivo studies have examined the association between redox status and the prognosis of acute coronary syndromes.We undertook a prospective, observational study of 137 patients who had been admitted because of an acute coronary syndrome. We determined glutathione peroxidase activity (a marker of systemic antioxidant status) and recorded clinical and angiographic features and cardiovascular events (cardiovascular death, reinfarction, readmission with a new ischemic event, or need for coronary revascularization).The mean age of the patients (78% of whom were men) was 61.7 +/- 10.9 years; 76% were admitted with non-ST-segment-elevation acute coronary syndrome. Left ventricular ejection fraction was normal in 61%. In the 23.4% who experienced cardiovascular events, glutathione peroxidase activity was higher (mean, 2.38 vs 1.76 mU/mg of protein; P < 0.01). Two-year event-free survival was lower in patients whose glutathione peroxidase activity was higher than the 50th percentile (63% vs 82%; P = 0.01). Multivariate analysis showed a direct independent relationship between glutathione peroxidase activity and cardiovascular events (hazard ratio, 3.72; 95% confidence interval, 1.53-9.02; P < 0.01).We conclude that patients who experienced acute coronary syndromes and events during follow-up had higher plasma glutathione peroxidase activity, and that glutathione peroxidase activity was an independent predictor of events during follow-up.

Oxidative stress-mediated arterial dysfunction in patients with metabolic syndrome: Effect of ascorbic acid

Arterial dysfunction is a hallmark of early atherosclerosis; however, its behavior in patients with metabolic syndrome (MS) is still unclear. We investigated the role of oxidative stress on ischemia-induced flow-mediated dilatation (FMD) in patients with MS. FMD and oxidative stress, as assessed by serum levels of 8-hydroxy-2-deoxy-2-deoxyguanosine (8-OHdG), were studied in 18 MS and 30 control subjects. Thereafter, in the 18 MS patients, FMD was assessed after iv infusion of 1 g vitamin C or placebo in a randomized, double-blind, crossover design; serial blood samples were taken in peripheral circulation before and after FMD to analyze 8-OHdG. Compared to controls, MS patients had higher 8-OHdG (p<0.001) and lower FMD (p<0.001); 8-OHdG and FMD were inversely correlated (R=-0.74; p<0.01). In MS patients, placebo administration did not change FMD, whereas vitamin C significantly enhanced it (p<0.001). After placebo, ischemia-induced FMD was associated with a significant increase in 8-OHdG (p<0.001), an effect that was counteracted by vitamin C. Vitamin C infusion was associated with an inverse correlation between the changes in FMD and oxidative stress (R=-0.67; p<0.01). The present study shows that arterial dilatation is impaired and that enhanced oxidative stress may play a key role in patients with MS.

The role of the antioxidant vitamin supplementation in the prevention of cardiovascular diseases

Industrial and technological revolutions have resulted in dramatic shifts in the diseases that are responsible for illness and death. In particular, cardiovascular disease (CVD) has emerged as the dominant chronic disease in many parts of the world. Diet, tobacco smoking, physical inactivity, obesity, lipid levels, hypertension and diabetes mellitus have contributed to their wide diffusion. Oxidative damage and the production of free radicals in the endothelium are two of the main factors involved in the pathogenesis of the atherosclerotic process that causes CVD. One of the more important results of basic research on dietetic regimes has shown that people who consume large amounts of fruits and vegetables have a lower incidence of CVD, stroke and tumours, but the specific mechanisms of these foods (which have an apparently protective effect) are still not completely clear. Possible reasons could include a greater consumption of fruit and vegetables, and an increased consumption of dietetic fibres. Recently, it been proposed that micronourishments with an antioxidant activity could be responsible for the reduction of chronic diseases. Research supplies a hypothetical mechanism by which antioxidant substances may be reducing the risk of atherosclerosis through the inhibition of oxidative damage. Appropriate nutritional practices are of central importance in managing risk and treatment of CVD; in fact, many current guidelines for a healthy general population contain nutritional recommendations to reduce the risk of these diseases. A large number of descriptive and case-control studies suggests that the consumption of many antioxidant vitamins (A, C and E) reduces the risk of CVD. Such data raises the following problem of whether supplementation of vitamins A, C and E emerges as being useful in the primary prevention of CVD. Many important studies involving a great number of participants have not confirmed this hypothesis and the results are often contradictory. This review examines the studies published in the literature that document the effect of supplementation with antioxidant vitamins (A, C and E) in the primary and secondary prevention of CVD due to an atherosclerosis process.

Associations of plasma 8-isoprostane levels with the presence and extent of coronary stenosis in patients with coronary artery disease

Oxidative stress may play a role in the development of atherosclerosis. The purpose of the present study was to explore the relationship between 8-isoprostaglandin F(2alpha) (8-iso-PGF(2alpha)) levels and the presence of coronary artery disease (CAD) and to also clarify whether 8-iso-PGF(2alpha) might add independently to measures of CAD extent. The study group consisted of 241 consecutive patients who were undergoing coronary angiography for suspected CAD. 8-iso-PGF(2alpha) levels were recorded for all participants. The analysis revealed a significant difference in 8-iso-PGF(2alpha) levels in patients with and without hypertension (P<0.001), in patients with diabetes relative to nondiabetic patients (P<0.05), and in males respect to females (P<0.001). A significant positive correlation was found between age and 8-iso-PGF(2alpha) levels (P<0.001). 8-iso-PGF(2alpha) levels correlated with the number of cardiovascular risk factors (P<0.001). 8-iso-PGF(2alpha) levels were higher in the CAD(+) respect to the CAD(-) groups (337.7+/-80.2 and 263.8+/-74.2 pg/ml and P<0.001). A stepwise elevation in the 8-iso-PGF(2alpha) levels was found depending on the number of affected vessels (P<0.001). The 8-iso-PGF(2alpha) levels showed a significant positive correlation with the numbers of >50 and >25% stenotic segments (P<0.001) and the extent score of coronary stenosis (P<0.001). The multivariate logistic regression analysis indicated 8-iso-PGF(2alpha) as an independent factor associated with CAD (odds ratio, 2.47 and P=0.001). The results suggested that 8-iso-PGF(2alpha) is associated with the presence of CAD in patients undergoing coronary angiography and is also related to the extent of coronary stenosis in Chinese population.

Menopause: a review on the role of oxygen stress and favorable effects of dietary antioxidants

Menopause is often accompanied by hot flashes and degenerative processes such as arteriosclerosis and atrophic changes of the skin that suggest an acceleration of aging triggered by estrogen lack. Therefore, hormone replacement therapy (HRT) has been considered the most suitable treatment for the above symptoms and processes. However, because of the possible serious side effects of HRT (especially the increased risk of thrombo-embolic accidents and breast cancer) there is a growing demand for alternative treatments of the symptoms and pathological processes associated with menopause. In agreement with the above, we review research that supports the concept that oxygen stress contributes to menopause and that some of its physiopathological effects may be prevented and/or treated improving the antioxidant defense of menopausic and postmenopausic women. Accordingly, a selection of micronutrients may be useful as a dietary supplement for protection against the decline of physiological functions caused by age-related oxygen stress. Since aging is accompanied by a progressive oxidation of the physiological sulfur pool, we emphasize the role of the vitamins B that help to maintain the GSH/GSSG ratio in its normal reduced state. Nutritional supplements should also include the key antioxidant vitamins C and E, as well as beta-carotene and the mineral micronutrients found in the oxygen radical-detoxifying enzymes glutathione peroxidase and superoxide dismutase. Moreover, the reviewed data suport the concept that other antioxidants such as lipoic acid and the precursors of glutathione thioproline (TP) and l-2-oxothiazolidine-4-carboxylic acid (OTC), as well as the soy isoflavones and the "coantioxidants" of an hydroalcoholic extract of Curcuma longa may help to prevent antioxidant deficiency with resulting protection of mitochondria against premature oxidative damage with loss of ATP synthesis and especialized cellular functions. Therefore, the administration under medical advice of synergistic combinations of some of the above mentioned antioxidants in the diet as well as topically (for skin protection) may have favorable effects on the health and quality of life of women, especially of those who cannot be treated with HR, suffer high levels of oxygen stress, and do not consume a healthy diet that includes five daily rations of fresh fruit and vegetables.

Oxidative stress and diabetic cardiovascular complications

Diabetes diagnoses are increasing at an alarming rate worldwide. The majority of diabetes-related deaths arise from cardiovascular complications such as myocardial infarction, stroke, and peripheral vascular disease. Oxidative stress has been demonstrated to be present in animal models as well as in patients with diabetes and has been suggested as a possible contributor to the accelerated atherosclerosis seen in diabetics. The generation of reactive oxygen species in diabetes occurs via several mechanisms and is initiated not only by glucose, but also by other substances that are found at elevated levels in diabetic patients. The resulting oxidative stress leads to a number of proatherogenic events. The elucidation of the mechanisms of oxidative stress in diabetes and their relationship with atherosclerosis could potentially identify molecular targets of therapy for this condition and its cardiovascular consequences.

Hyperglycemia-induced reactive oxygen species and impaired endothelial progenitor cell function

Vascular complications in diabetes are a significant source of human morbidity and mortality, affecting multiple organ systems and persisting despite tight glucose control. Many of these complications can be linked to impairments in vasculogenesis, the process by which circulating and bone marrow-derived endothelial progenitor cells (EPCs) contribute to new vessel formation. Recent evidence suggests that hyperglycemia alone, through the mitochondrial overproduction of reactive oxygen species (ROS), can induce changes in gene expression and cellular behavior in diabetes. In this review, we examine how hyperglycemia-induced overproduction of ROS could explain EPC impairments observed in diabetes. Experimentally, impairments in EPC function prevent new blood vessel growth and are potentially reversible by manipulations to decrease ROS. Novel strategies aimed at reducing hyperglycemia-induced ROS may be a useful adjuvant to antihyperglycemic therapies in the restoration of vasculogenesis and the prevention of diabetic complications.

An immune origin of type 2 diabetes?

Subclinical, low-grade systemic inflammation has been observed in patients with type 2 diabetes and in those at increased risk of the disease. This may be more than an epiphenomenon. Alleles of genes encoding immune/inflammatory mediators are associated with the disease, and the two major environmental factors the contribute to the risk of type 2 diabetes-diet and physical activity-have a direct impact on levels of systemic immune mediators. In animal models, targeting of immune genes enhanced or suppressed the development of obesity or diabetes. Obesity is associated with the infiltration and proinflammatory activity of macrophages in adipose tissue, and immune mediators may be important regulators of insulin resistance, mitochondrial function, ectopic lipid storage and beta cell dysfunction or death. Intervention studies targeting these pathways would help to determine the contribution of an activated innate immune system to the development of type 2 diabetes.

Evaluation of serum neopterin, high-sensitivity C-reactive protein and thiobarbituric acid reactive substances in Egyptian patients with acute coronary syndromes

The present study evaluated serum neopterin, high-sensitivity C-reactive protein (hs-CRP) and thiobarbituric acid reactive substances (TBARS) in Egyptian patients with acute coronary artery disease. Thirty-six patients with unstable angina aged (mean +/- SD) 61.3+/-9.4 years, 29 patients with myocardial infarction aged 58.2+/-8.7 years and 24 sex- and age-matched control subjects were included in the study. Neopterin levels were significantly higher in patients with myocardial infarction and those with unstable angina than in the healthy control group (P<0.001). The serum level of neopterin in the control group (median [range]) was 3.25 nmol/L (1.25 nmol/L to 5.4 nmol/L), whereas in patients with unstable angina and those with myocardial infarction, neopterin levels were 10.4 nmol/L (3.5 nmol/L to 15.2 nmol/L) and 12.6 nmol/L (3.25 nmol/L to 17.8 nmol/L), respectively. Levels of hs-CRP and TBARS were also significantly higher in patients with unstable angina and those with myocardial infarction than in the healthy control group (P<0.01). The medians (ranges) of hs-CRP were 4.8 mg/L (2.5 mg/L to 9.9 mg/L), 12.0 mg/L (4.6 mg/L to 31.0 mg/L) and 12.3 mg/L (7.5 mg/L to 32.1 mg/L) in the control group, patients with unstable angina and those with myocardial infarction, respectively. The means +/- SD of TBARS in the control group, patients with unstable angina and those with myocardial infarction were 0.64+/-0.17 mumol/L, 1.17+/-0.31 mumol/L and 1.17+/-0.49 mumol/L, respectively. TBARS positively correlated with hs-CRP and neopterin levels. Furthermore, when both patients and controls were classified according to their smoking status, significantly higher levels of neopterin and TBARS were found in the smokers of each subgroup than in the nonsmokers.In conclusion, the present study found a higher level of neopterin, hs-CRP and TBARS in patients with coronary artery disease. Serum neopterin and hs-CRP positively correlated with the level of TBARS. The authors suggest that triggering factors (eg, smoking, high cholesterol, elevated body mass index or raised blood pressure) may lead to increased oxidative stress, which induces an inflammatory insult leading to higher levels of inflammatory markers such as neopterin and hs-CRP.